What Are Soap Mummies?

In 1875, the construction of a new train depot in downtown Philadelphia required that a few graves be exhumed. Although bodies in a graveyard are usually reduced to skeletons within a couple of decades, two of the bodies had hardly decayed, instead appearing to be fully encased in a waxy, soap-like substance. The bodies were dubbed The Soap Lady and Soapman, and now appear in the Mütter Museum and the Smithsonian, respectively. But what caused them to become mummies in the first place? It's called saponification. The process requires a warm, damp, alkaline environment, which existed for these corpses after water seeped into their caskets, bringing alkaline soil with it. The conditions make a great home for a certain type of anaerobic bacteria, which convert a corpse's body fat into a greasy substance known as adipocere. The adipocere can completely encase the corpse, halting the decay process and preserving the body for years. This preservation is great for archaeologists, who have X-rayed soap mummies to learn more about their history. For graveyards, however, the phenomenon isn't so pleasant. Many cemeteries recycle graves every 15-25 years, since bodies should decompose to skeletons in that time. When bodies turn into soap mummies, cemeteries can be left with too many bodies and not enough plots to put them in.

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Adipocere, also known as grave wax or corpse wax, is a greasy or waxy substance that's made of decomposing fat. Its production is known as saponification and results when a body is oxygen-free, warm, and moist with certain bacteria present.
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Eyeballs deflate when you die. Some medical examiners measure this deflation to estimate how long ago a corpse died.
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A dead body changes colors as bacteria feed on its insides, first to green, then purple, then black.
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